S:
Standard Reference Materials (SRMs) - NIST supports accurate and compatible measurements by certifying and providing over 1300 Standard Reference Materials® with well-characterized composition or properties, or both. These materials are used to perform instrument calibrations in units as part of overall quality assurance programs, to verify the accuracy of specific measurements and to support the development of new measurement methods. [U.S. Department of Commerce (DOC), National Institute of Standards and Technology (NIST), Various laboratories]